This invention relates to a cutting segment of the type adapted to be mounted on the periphery of a circular metal disc to form a circular cutting wheel having an outer cutting surface adapted for cutting stone, concrete and the like.
It is common practice to mount a plurality of cutting segments to the periphery of a circular steel disc to form a circular cutting wheel, that is then rotated and translated through concrete or stone in order to cut the concrete or stone. The cutting segments typically consist of solid bodies of diamond dust or diamond fragments used as an abrasive and held dispersed and embedded in metal. Often, the cutting segments are manufactured by cold pressing powdered metal containing diamond dust or diamond fragments into the desired shape and then further pressing this intermediate shape at high temperature and pressure to harden the segment. Segments prepared in this manner, or any other suitable manner, are secured to the periphery of a circular metal disc by welding, brazing or silver soldering. Cutting wheels thus made are then mounted to various types of mobile and stationary saws for use in cutting, among other things, stone, concrete, tile and refractory products.
In cutting materials of the described type, it is important to maintain a straight or true cut. Such a cut reduces the frictional wear on the cutting segments and helps ensure that the wear that does occur is even. Additionally, a straight cut reduces the number of subsequent steps required to prepare the workpiece for its ultimate use and helps prevent chipping that might otherwise occur at the edge of the cut. Further, it facilitates efficient cutting and optimizes the use of the cutting machinery.
To provide a straight cut, it is known in the art that each cutting segment can be constructed so that differential wearing occurs during use on different portions of the cutting surface so that a concave edge or arcuate groove results. As one continues to cut the stone or concrete, this groove wears a similar profile of opposite orientation in the workpiece. The arcuate groove formed in each segment nests with the profile of opposite orientation worn in the workpiece so as to create an effect very much like a train wheel on a rail. The profile in the workpiece guides the cutting wheel through the workpiece resulting in the desired straight cut.
Cutting segments of different types that provide a concave edge or arcuate groove in the cutting surface have been suggested in the past, but they all have significant drawbacks. For instance, the cutting segment suggested by U.S. Pat. No. 3,203,774 achieves differential wearing on the cutting surface by providing a segment of layered construction. Two outer side layers are provided which contain an increased content of abrading material which results in more wear over the central layer of the segment. Such a segment is expensive to make due to its layered construction and inevitably leads to defects in manufacturing that can only be detected after the segment is in use. Additionally, it has been shown that segments with a layered construction are not capable of production rates that otherwise might be obtained because the different segments tend to separate under high stress.